METHOD FOR MANUFACTURING A PRINTING MOLD

Abstract

The invention relates to a method for manufacturing a printing mold (40), comprising the following steps: providing a master mold (10) having a structured surface with non-stick properties, the structured surface having a plurality of patterns (20); modifying only a portion (100) of the structured surface so as to cause said portion to lose its non-stick properties, said portion (100) comprising at least one of the patterns (20); forming a substrate on the structured surface, the substrate comprising an printing layer structured by the patterns (20); separating (S4) the substrate from the master mold (10) to obtain the printing mold (40), a portion (311) of the printing layer remaining attached to the modified portion (100) of the structured surface. Figure to be published with the abbreviation: Figure 1F

Description

Title of the invention: METHOD OF MANUFACTURING A PRINTING MOLD TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of lithography by printing. The invention relates more particularly to a method of manufacturing a printing mold commonly called an intermediate mold or working mold, from a master mold. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Among the lithography techniques used in the microelectronics industry for the fabrication of integrated circuits, nanoprinting is attracting increasing interest. This technique is based on printing a deformable material, typically a resin, with a mold. The mold contains patterns that are transferred into the resin during printing and whose dimensions are generally between a few nanometers and several hundred micrometers.

[0003] There are two types of printing molds: so-called "rigid" molds and so-called "flexible" molds.

[0004] One advantage of rigid molds, for example based on silicon substrates, is their mechanical resistance, making them reusable many times.

[0005] One advantage of flexible molds, generally made of polymer materials, lies in their ability to deform and thus achieve consistent contact across the entire surface to be printed, resulting in a more uniform distribution of the pressure applied by the mold. For this reason, flexible molds are generally used to print large surface areas, for example, on substrates with a diameter greater than 100 mm. Furthermore, their flexibility reduces the risk of breakage in the presence of dust between the surface to be printed and the mold. Demolding a flexible mold pressed against a layer of lithography resin is facilitated, as it can be done by peeling.

[0006] Flexible or rigid working molds can be made from a primary mold, commonly called a master mold. One face of this master mold has patterns forming a negative image of the relief to be imparted to the working molds. The same master mold can then be used to manufacture several working molds, which tends to reduce the manufacturing cost of these molds.

[0007] The master mold is generally produced using manufacturing technologies from the microelectronics industry (photolithography, etching, etc.) from a substrate made of semiconductor material, for example silicon.

[0008] The working mold is generally obtained from the master mold by depositing a liquid or semi-liquid polymer material called resin onto the master mold. This polymer material is intended to form a portion of the working mold, namely the part bearing the patterns. To form a flexible mold, a flexible film of polymer material can then be laminated onto the stack formed by the master mold and the resin layer. Alternatively, to form a more rigid mold, a rigid handle can be applied over the polymer material. The assembly is then exposed to electromagnetic radiation (generally ultraviolet radiation) and / or a heat treatment to which the resin is sensitive. The resin is thus hardened. It exhibits preferential adhesion to the flexible film or the rigid handle rather than to the master mold, which allows demolding at the level of the master mold.The flexible film or rigid handle and the hardened resin layer together form the working mold. The working mold has patterns in the hardened resin layer with the opposite polarity to those present on the master mold (a raised pattern becomes a recessed pattern, and vice versa).

[0009] The structured surface (i.e., having the patterns) of the master mold can be covered with a non-stick layer to facilitate the removal of the working mold.

[0010] One disadvantage of this manufacturing process is that the working molds made from the same master mold are all identical, which therefore requires multiplying the master molds. Summary of the invention

[0011] There is therefore a need for a printing mold manufacturing process that can be adapted to be able to manufacture different molds from the same master mold.

[0012] According to one aspect of the invention, this need is met by providing a method for manufacturing a printing mold, comprising the following steps: • provide a master mold having a structured surface with a non-stick character, the structured surface having a plurality of patterns; • modify only a portion of the structured surface so as to cause said portion to lose its non-stick character, said portion comprising at least one of the patterns; • form a support on the structured surface, the support comprising a layer of printing structured by the patterns; • separate the support from the master mold to obtain the printing mold, with part of the printing layer remaining attached to the modified portion of the structured surface.

[0013] In a preferred embodiment of the manufacturing process, the master mold comprises a substrate and a non-stick layer disposed on the substrate and the structured surface having the non-stick character belongs to the non-stick layer.

[0014] According to a first development of this preferred embodiment, the portion of the structured surface is modified by degrading a portion of the non-stick layer.

[0015] The portion of the non-stick layer is preferably degraded by a point or by exposure to an electron beam, a laser or a chemical solution.

[0016] According to a second development, the portion of the structured surface is modified by completely removing a portion of the non-stick layer.

[0017] The formation of the support on the structured surface may include the following sub-steps: • apply a layer of hardenable resin to the structured surface; • bring a support layer into contact with the resin layer hardenable; and • harden the resin; the printing layer of the support being formed by the hardened resin layer.

[0018] Alternatively, the formation of the support on the structured surface may comprise the following sub-steps: • apply a layer of hardenable resin onto a support layer; • Press the layer of curable resin against the textured surface; and • harden the resin; the printing layer of the support being formed by the hardened resin layer.

[0019] The support layer can be a flexible film or a rigid substrate.

[0020] The process may include, after the support separation step, a step of restoring the structured surface having the non-stick character. BRIEF DESCRIPTION OF THE FIGURES

[0021] Other features and advantages of the invention will become clear from the description given below, by way of example and not limitation, with reference to the accompanying figures, among which: • Figures IA to 1F schematically represent a preferred implementation of a printing mold manufacturing process according to the invention; and • Figures 2A to 2C schematically represent a lithography process using the manufactured printing mold.

[0022] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED DESCRIPTION

[0023] Figures IA to 1F illustrate steps SI to S4 of a printing mold manufacturing process according to a preferred embodiment of the invention. The printing mold, also called a working mold or intermediate mold, can be used in an impression lithography process for the manufacture of microelectronic devices. Thus, the expression "impression lithography mold" can also be used to refer to the printing mold.

[0024] In this preferred embodiment, the printing mold is flexible. Generally speaking, the flexibility of the printing mold (as well as the flexible substrate and flexible film described below) refers, alternatively or cumulatively: • its elastic deformation capacity to conform to a non-planar printing surface during printing, thus achieving consistent contact over the entire printing surface; • its elastic deformation capacity during at least one stage of mold use, such as lamination onto a surface to be printed or peeling; • with a Young's modulus of less than 1 GPa of its material or materials; • its bending deformation capacity with a radius of curvature less than or equal to 1 m, preferably less than or equal to 5 cm.

[0025] With reference to [Fig. 1A], the process first comprises a step SI of supplying a master mold 10, or master template, from which the printing mold will be manufactured. The master mold 10 has a structured surface 10A, that is, a surface with patterns 20. The patterns 20 of the master mold 10 are topographic patterns, in other words, recessed or raised patterns. Here, the patterns 20 considered are recessed patterns. They can be holes, for example in the shape of a right cylinder, and / or lines.

[0026] The master mold 10 can be made from a substrate 11, for example silicon, using manufacturing technologies employed in the microelectronics industry, typically by photolithography and etching.

[0027] The motifs 20 may have dimensions ranging from 1 nm to 500 pm, preferably between 50 nm and 1 pm. In particular, the height of the motifs, measured perpendicular to the main faces of the substrate 11, can be between 50 nm and 500 nm. Since the printing mold will have patterns of the same dimensions as the patterns 20 of the master mold, but with a polarity (negative image), the printing mold produced can be described as a nano-printing mold (insofar as it allows the printing of patterns of nanometric dimensions).

[0028] The structured surface 10A of the master mold 10 has a non-stick character, in particular to facilitate the subsequent demolding of the printing mold.

[0029] In this preferred embodiment, the master mold 10 comprises, in addition to the substrate 11, a non-stick layer 12 disposed on the substrate 11. The structured surface 10A, having the non-stick character, then belongs to the non-stick layer 12. In other words, the structured surface 10A is constituted by the non-stick layer 12.

[0030] In [Fig. 1A], the patterns 20 are formed (preferably by engraving) in the substrate 11, from one of its main faces, and the non-stick layer 12 covering the patterns 20 has a constant thickness. Thus, the aspect ratio of the patterns 20 is maintained.

[0031] The non-stick layer 12 is for example a trichlorofluorosilane type coating deposited (in a conforming manner) on the substrate 11 by a chemical vapor deposition (or CVD) technique.

[0032] The master mold 10 can alternatively comprise a substrate 11 whose main faces are flat and a non-stick layer 12, of variable thickness, in which the patterns 20 are formed.

[0033] In an embodiment not shown in the figures, the master mold 10 comprises only the substrate 11, one face of which is structured to form the patterns 20. Indeed, the substrate 11 may be made of a material that inherently (or intrinsically) possesses the desired adhesive properties, for example, silicon with a water contact angle of less than 10°. Alternatively, the substrate 11 may undergo a surface treatment enabling it to acquire these adhesive properties. Examples include oxygen plasma or hexamethyldisilazane (HMDS) vapor deposition.

[0034] In step S2 of [Fig. 1B], only a portion 100 of the structured surface 10A is modified so as to cause this portion 100 to lose its non-stick character. The portion 100 contains at least one of the patterns 20 of the structured surface 10A. The remaining, unmodified portion of the structured surface 10A also includes one or more patterns 20.

[0035] In the preferred embodiment of Figures 1A-1F, the modification of the portion 100 of the structured surface 10A can be accomplished either by degrading a portion of the non-stick layer 12, or by removing entirely (i.e. over the entire thickness of the non-stick layer 12) a portion of the non-stick layer 12, for example by engraving.

[0036] In the event of degradation, the anti-adhesive layer 12 remains but becomes adhesive. The degradation may consist, in particular, of an increase in the roughness of the anti-adhesive layer 12 or a change in its chemical affinity. The anti-adhesive layer 12 may be degraded by a tip such as that of an atomic force microscope or by exposure to an electron beam, a laser, or a chemical solution. By way of example, the anti-adhesive layer 12 is degraded (locally) by exposure to an electron beam at a dose of 250 pc / cm².

[0037] In the case of etching, the substrate 11, which has adhesive properties, is partially exposed. The non-adhesive layer 12 can be etched (locally) by an oxygen-based plasma, for example.

[0038] The process then comprises a step S3 of forming a support 30 on the structured surface 10A of the master mold 10. This support 30 is flexible and intended to form the flexible printing mold. It comprises a printing layer 31 structured by the patterns 20 of the master mold 10, and in particular by the pattern(s) 20 contained in the modified portion 100 of the structured surface 10A (see [Fig. 1E]). Thus, the printing layer 31 comprises (printing) patterns 20' corresponding to those of the master mold (of the same dimensions but in negative: here, a recessed pattern 20 becomes a raised pattern 20').

[0039] The printing layer 31 is formed from a deformable material, so that it can be structured by the patterns 20. This deformable material is preferably a polymer material in a liquid or semi-liquid (viscous) state, for example a curable resin.

[0040] Figures IC to IC illustrate a first embodiment of step S3 for forming the support 30. In a first substep S3 / 1 represented by [Fig. 1C], a layer of curable resin 31' is deposited on the structured surface 10A. Preferably, the layer of curable resin 31' fills all the patterns 20 of the master mold 10 and forms an additional thickness on the surface of the master mold 10. It is, for example, deposited by spin-coating. Then, in a second substep S3 / 2 represented by [Fig. 1D], a support layer, here formed by a flexible film 32, is brought into contact with the layer of curable resin 31'. The flexible film 32 can be laminated onto the layer of curable resin 31'. Finally, the resin is hardened during a third sub-step S3 / 3 represented by [Fig.lC].

[0041] In a second embodiment, step S3 of support 30 training comprises the following sub-steps: • the deposition of a layer of hardened sand resin on a support layer such as a flexible film; • pressing the layer of curable resin against the structured surface; and • the hardening of the resin;

[0042] In these two embodiments of step S3, the printing layer 31 of the support 30 is formed by the hardened resin layer.

[0043] The resin can be photo-curable and / or thermo-curable (also referred to as photosensitive or thermosensitive resin). In other words, it is hardened (or crosslinked) by exposure to electromagnetic radiation (typically UV radiation) and / or heat treatment.

[0044] The curable resin may contain an inorganic filler to improve the properties of the printing layer 31, typically its mechanical strength. The cured resin then forms a composite material comprising a polymer matrix and an inorganic filler. The inorganic filler is, for example, in the form of particles.

[0045] The flexible film 32 is preferably made of a polymer material (alone) or a composite material. Polydimethylsiloxane (PDMS) may be cited as an example. Its thickness is advantageously between 1 µm and 10 µm. It gives the flexible mold its mechanical properties. Thus, its Young's modulus is advantageously less than 1 GPa and / or it is capable of undergoing flexural deformation with a radius of curvature less than or equal to 1 m, preferably less than or equal to 5 cm.

[0046] With reference to [Fig. 1F], the manufacturing process includes a step S4 called demolding consisting of separating the support 30 from the master mold 10 to obtain the printing mold 40. This separation can in particular be carried out by peeling.

[0047] A portion 311 of the printing layer 31 remains attached to the modified portion 100 of the structured surface 10A, which is made adhesive in step S2 of [Fig. 1B]. The printing mold 40 is formed by the support 30, which here comprises the remaining portion 312 of the printing layer 31 and the flexible film 32. One or more patterns 20 of the master mold 10 located in the modified portion 100 are thus "plugged" by this portion 311 of the printing layer 31 and are not found in the printing mold 40.

[0048] Thus, the adhesive or non-adhesive character of the structured surface 10A, the non-adhesive layer 12 or the substrate 11 is understood in relation to the material (possibly composite) of the printing layer 31.

[0049] The manufacturing process thus makes it possible to select which pattern(s) 20 of the master mold 10 will not be replicated in the printing mold 40. It is therefore possible, thanks to this process, it is possible to produce from the same master mold 10 (cf. [Fig.lA]) printing molds with different pattern distributions.

[0050] After the fabrication of a first printing mold 40, the process may include a step of restoring the structured surface 10A having the non-stick property, thus returning to the stage of [Fig. 1A]. The part 311 of the printing layer 31 that remained stuck to the master mold 10 can be removed simultaneously.

[0051] In the preferred embodiment described in relation to Figures 1A-1F, this restoration step may include a substep of removing the anti-adhesive layer 12, preferably by wet means (peroxymonosulfuric acid solution for example), and a substep of forming a new anti-adhesive layer on the exposed substrate 11.

[0052] Then, a second printing mold can be manufactured by again performing steps S2, S3 and S4 described above. The second printing mold is differentiated from the first printing mold by changing the modified portion 100 of the structured surface 10A in the location and / or its extent (in other words, by selecting at least one other pattern 20 or by decreasing the number of patterns 20 in the portion 100).

[0053] The different printing molds can be used in the manufacture of the same microelectronic device or to manufacture different microelectronic devices.

[0054] In an embodiment not shown in the figures, a rigid printing mold is obtained by replacing the flexible film 32 with a rigid substrate, also called a rigid handle (as a support layer), in the process of Figures 1A-1F (and more particularly in the steps of Figures 1D to 1F). The rigid substrate is, for example, made of glass, quartz, silicon, or a metal. It is brought into contact with the master mold 10 and demolded either parallel to the plane of the master mold 10 or at an angle (this facilitates detachment). As before, the deformable material forming the printing layer 31 of the support 30 can be deposited either onto the master mold 10 (and then the rigid substrate is placed on top of it) or onto the support layer formed here by the rigid substrate.

[0055] The manufacturing process finds particularly advantageous applications in the field of electronic identification or that of securing electronic chips, fields where the aim is to form sets of different patterns.

[0056] Figures 2A to 2C illustrate an example of use of the printing mold 40: a lithography printing process.

[0057] The lithography process includes an printing step SI 1, using the printing mold 40, of patterns 53 in a layer of printable material 51 disposed on a target substrate 52.

[0058] When the printable material layer 51 is formed of a curable resin (thermo-curing and / or photo-curing), the printing of the patterns 53 can comprise two sub-steps SI 1 / 1 and SI 1 / 2 represented by Figures 2A and 2B. In SI 1 / 1 (see [Fig. 2A]), the printing mold 40 is pressed against the resin layer 51 so as to transfer the patterns from the printing mold 40 into the resin layer 51. Then, in SI 1 / 2 (see [Fig. 2B]), the resin is cured (with the printing mold 40 still applied against the resin layer 51).

[0059] At the end of the printing step SI, a printed layer 51', i.e. comprising patterns 53 corresponding to those of the printing mold 40, is obtained.

[0060] With reference to [Fig.2C], the lithography process then includes a demolding step S12 consisting of separating the printing mold 40 from the printed layer 51'. Demolding can in particular be carried out by peeling in the case of a flexible printing mold.

[0061] Finally, after demolding, the lithography process may include a step of transferring the patterns 53 from the printed layer 51' into the target substrate 52, for example by etching through the printed layer 51' (the printed layer 51' thus serving as an etching mask).

Claims

Demands

1. A method for manufacturing a printing mold (40), comprising the following steps: - providing (S1) a master mold (10) having a structured surface (10A) with a non-stick character, the structured surface (10A) having a plurality of patterns (20); - modifying (S2) only a portion (100) of the structured surface (10A) so as to cause said portion to lose its non-stick character, said portion (100) comprising at least one of the patterns (20); - forming (S3) a support (30) on the structured surface (10A), the support (30) comprising a printing layer (31) structured by the patterns (20); - separate (S4) the support (30) from the master mold (10) to obtain the printing mold (40), a part (311) of the printing layer (31) remaining attached to the modified portion (100) of the structured surface (10A).

2. A method according to claim 1, wherein the master mold (10) comprises a substrate (11) and a non-stick layer (12) disposed on the substrate (11) and wherein the structured surface (10A) having the non-stick character belongs to the non-stick layer (12).

3. A method according to claim 2, wherein the portion (100) of the structured surface (10A) is modified by degrading a portion of the non-stick layer.

4. A method according to claim 3, wherein the portion of the non-stick layer (12) is degraded by a point or by exposure to an electron beam, a laser or a chemical solution.

5. Method according to claim 2, wherein the portion (100) of the structured surface (10A) is modified by completely removing a portion of the non-stick layer (12).

6. A method according to any one of claims 1 to 5, wherein the formation of the support (30) on the structured surface (10A) comprises the following substeps: - depositing (S3 / 1) a layer of curable resin (31') on the structured surface (10A);

7.

8.

9. - bring (S3 / 2) a support layer into contact with the curable resin layer (31'); and - harden (S3 / 3) the resin; the printing layer (31) of the support (30) being formed by the hardened resin layer. A method according to any one of claims 1 to 5, wherein the formation of the support (30) on the structured surface (10A) comprises the following substeps: - apply a layer of hardenable resin onto a support layer; - press the layer of hardenable resin against the textured surface; and - harden the resin; the printing layer of the support being formed by the hardened resin layer. A method according to any one of claims 6 and 7, wherein the support layer is a flexible film (32) or a rigid substrate. A method according to any one of claims 1 to 8, further comprising, after the step (S4) of separating the support (30), a step of restoring the structured surface (10A) having the non-stick character.